Interestingly, GW astronomy is not the only channel to probe PBHs. They can be tested through their direct or indirect imprints on many more astrophysical and cosmological observables. The wealth of physical processes showing traces of their influence has been used to place tight bounds on the abundance of PBHs, which is becoming increasingly constrained [1]}. Such bounds, however, crucially depend on the mass function of the specific PBH model, which is often assumed to be monochromatic to simplify computations. In fact, broad mass functions are required to explain GW observations, which often relaxes other constraints, and PBHs can still constitute a sizeable fraction of the CDM.
